Transmitter device



March 5, 1935. H. EBERHARD 1,993,435

TRANSMITTER DEVICE Filed April 19, 1932 2 Sheets-Sheet l 2 y 5 m M3 437"" pi I." 1I\JZJ Jnren/or:

ZK IA MAW March 5, 1935. H, EBERHARD 1,993,436

TRANSMITTER DEVICE Filed April 19, 1932 2 Sheets-Shget 2 I D k/ z v I] 1I J/Wenfor:

Kumd wmwx Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE In Germany'1 Claims.

The subject matter of the present invention concerns a novel type ofsmall portable quartzcontrolled transmission apparatus. By reason of itscompact construction the same is particularly I suitable for police orcriminal investigation work, or quite generally in such cases in whichit is desired to transmit wireless signals ininconspicuous fashion tonot too great distances. The size of the apparatus is roughly that of acartridge case, i. e., of pocket size. At the same time the apparatuscontains a transmission valve of approximately 1 watt.

Specifically, the compact construction is obtained by reason of the factthat as anode battery there is employed a battery having single elementscapable of being set together and consisting of circular or rectangulardiscs with a cross-sectional area amounting to approximately 4 sq. cm.The transmission valve employed also possesses extremely smalldimensions. A transmission valve of roughly 1 watt has successfully beendesigned the bulb of which possesses a diameter of approximately 15 mm.and a length of approximately 60 mm. The valve is fitted without asocket, and requires for its operation a heating potential of 2 voltsand an anode potential of approximately 5560 volts. Anode currentssuflicient for short ranges were obtained, however, with even 20 volts.Of particular importance as regards reliable operation of the smalltransmitter according to the invention is the use of a piezo-electriccrystal, for example quartz. The operating waves may have a lengthamounting to 20-40 metres. Without a control crystal of this nature itwould be wholly impossible to transmit signals of a kind capable ofbeing received at a receiving station. The movements of the operatorwhen walking result in capacitative detuning of such nature that thetransmission of a constant wave does not enter into the question withoutthe use of a control crystal. If on the other hand quartz is employed inthe manner known per se for controlling the transmitter, perfectlysatisfactory conditions of operation are obtained. Thus, for example, ifpolice doing street duty are equipped with the small transmitteraccording to the invention, faultless reception may be obtained by meansof a receiving station, which might possibly be fitted in a car in anadjoining street. To enable the transmission apparatus to be carriedwithout creating attention, and more particularly to operate the sameinconspicuously, the transmission apparatus according to the inventionis, in accordance with the additional subject matter of April 21, 1931the invention, so constructed that the same may be carried about thebody by means of a strap. In the strap itself there is then sewn theloop composed of one or more windings acting as aerial.

To obtain the maximum degree of constancy of the operating wave there isnot employed, in accordance with the additional subject matter of theinvention, a holder of any of the known kinds for the piezo-electriccrystal, but specifically for this purpose a space-economizing mountingwas designed, which is also suitable for other purposes. The same isparticularly characterized by the fact that the heat developed in thevibrating quartz is rapidly discharged, and accordingly during theoperation of the quartz there is avoided any change in the naturalelastic wave thereof. The mounting for the control quartz consists indetail of two thin metal discs, which act as electrodes and are held ata certain distance apart by means of an insulating ring. Thepiezo-electric crystal is mounted in the hollow space of the casing thusformed. In order to ensure that the spacing between the quartz and theelectrodes does not vary, which is of particular importance when usingthe same for a portable apparatus, pressure is exerted on the crystaldisc by a spring disc.

The invention is described with reference to the drawings, which show afew forms of embodiment.

Fig. 1 represents a complete view of the small transmitter.

Fig. 2 shows a watchman equipped with the apparatus.

Fig. 3 is a view of the interior or a transmitter according to theinvention, and shows the structural arrangement of the single parts.

Fig. 4 shows the circuit diagram of the transmitter according to Figs.1-3.

Fig. 5 illustrates a form of embodiment of the inductance acting asaerial.

In Figs. 6-8 there is shown the manner in which the small transmitteraccording to the invention may be fitted with an aerial 01' the rodtype.

Fig. 9 is a cross-section through a transmitter valve according to theinvention.

Fig. 10 is a section through the oscillator according to the invention.

In the single figures the corresponding parts have been designated bythe same reference characters. Thus, for example, 1 is the ionic valveconsisting of the anode 2, the grid 3, the cathode 4, which are mountedin the lass bulb 5. About the glass bulb there is wound the choke 6which, in the same manner as the piezo-electric crystal '7, is connectedbetween the grid and the cathode of the valve. The heating current forthe cathode 4 may be supplied by the battery 9, and the anode current bythe anode battery 10. There is, however, no objection to employing inplace of an anode battery a vibrator transformer fed by the heatingbattery, as covered by the patent application Ser. No. 602,865 Valveconnection system" dated April 1932. As will be recognized from Fig. 3,there is arranged behind the heating battery 9 the anode battery 10. Foradaptation to the limited conditions of space, the anode battery may bebuilt up of single elements arranged in vertical columns. Thus, forexample, the anode battery may consist of single discs of zinc andcarbon. The single discs may possess a cross-sectional area amounting toapproximately 4 sq. cm. The electrolyte may consist of a filling asknown in the case of dry elements. In the present example theelectrolyte is made up as follows: 100 c. cm. water, 25 c. cm.sal-ammoniac, 10 c. cm. zinc chloride, and 0. cm. calcium chloride and acertain amount of gelatine.

The electronic valve 1, for the purpose of obtaining a considerableslope or large output with minimum requirement for space, is providedwith two entirely separate electrode systems constructed on the lines ofFig. 9, wherein the corresponding electrodes may be preferably connectedin parallel within the valve. The diameter of the anode of eachelectrode system shown in cross-section in Fig. 9 may amount toapproximately 4 mm., the diameter of the grid to 1 mm. As cathode theremay be employed a 30 a tungsten filament. The single windings of eachgrid may be furnished each with one single transverse bar. Since inemploying the valve illustrated in Fig. 9 for the small portabletransmitter in Figs. l-4, it is not a matter of employing valves ofconsiderable durability, but of obtaining within a brief space of time amaximum amount of energy from a valve of small dimensions, the valve issystematically overheated. With an anode potential of approximately 50volts and a heating potential of approximately 2 volts it is thenpossible to obtain an emission of roughly m. a. The slope of the valveis then approximately 2 m. a. per volt, and the reciprocal of theamplification factor roughly 12-15%. The ionic valve illustrated in Fig.4 or 9 possesses a cathode produced according to the metal vapourprocess, that is to saybarium in the form of vapour is deposited on thetungsten filament, for example by means of a chemical reaction. Thedeposition of barium is known per se and is not claimed in thisapplication.

The connection according to Fig. 4 is completed by the bridgingcondenser 11, the morse key 12, the rotary plate condenser, which isadjustable from the exterior, for example by means of a screw-driver,and by the loop 24 acting as aerial.

The key 12 is so arranged that signals may be transmitted withoutattracting attention. The key of the apparatus located in the pocket ofthe operator may accordingly be operated in the pocket in inconspicuousfashion. The key or other interrupting means for the anode circuitoperated in morse rhythm may be arranged of course at any other suitablepoint.

The loop 14 in the arrangement according to Fig. 1 is fitted in thestrap of the apparatus, by means of which strap the apparatus may becarried, as illustrated in Fig. 2. The coil acting as aerial may also beconstructed as shown in Fig. 5, or in another suitable manner. As shownin Fig. 5 the coil 14 may consist of two circular wire windings, whichare maintained at a constant distance apart, for example amounting to 15mm., with the assistance of two distance pieces 15. In the arrangementaccording to Fig. 5 there is employed for the coil an enamelled copperwire of 1 mm. thickness. The inner winding possesses a diameter ofapproximately 25 cm. The self-supporting coil 14 may in the embodimentaccording to Fig. 5 be worn under the coat or in the jacket andconnected with the condenser 13 or the transmitter connection system bymeans of special wires.

There is no objection, for improving the radiation, to employing inplace of a coil for the aerial an aerial of the open type, for example arod aerial. Such an aerial is shown in Figs. 6-8. There may be employeda dipole aerial on the lines of a Hertz oscillator, i. e.,thetransmitter is arranged at the centre between two conductors, the lengthof each of which may amount to one-quarter of the wave length. It is notabsolutely essential that the two conductors are located in the samedirection. Thus, for example, the vertically disposed rod aerial 16 (asit is shown in Fig. 6) may be connected with the transmission apparatus17 at the bottom. At the lower end of the apparatus there is connectedthe horizontally disposed strand 18 taken towards the right.

According to the additional subject matter of the invention, therod-shaped aerial is constructed in telescopic fashion on the lines of atripod. In the form of embodiment shown in Fig. 6 three metal rods, forexample aluminium tubes, 19, 20, 21 are arranged one within the other,so as to form a telescope. At the lower end of the tube 21 there isprovided an insulating member 22, and beyond the same a point 23, bymeans of which the aerial may be stuck in the ground. The insulatingmember 12 serves the purpose of securing the apparatus 17 to the aerial16, 18. This is preferably performed by furnishing the apparatus 17 withfishplates 24,

25 (Fig. 7). Through the medium of these plates the connections of theoscillatory circuit lead to the aerial, so that when fixing in theapparatus 1'7 the latter is already connected with the aerial.

It is also of importance that as is shown in Fig. 3 a switch 26 may beprovided, which permits of the connection and disconnection of thebatteries without opening the box 2'7.

In Fig. there is shown a cross-section taken through the mounting forthe piezo-electric crystal 7. For the electrodes there are employed twothin metal discs 28 and 29, composed for example of nickel. These areheld at a certain distance apart by a ring of pertinax or other suitablematerial. In the hollow space thus formed there is located the quartzdisc '7. There is also provided a spring disc 30, which rests withsuitable bias on the one hand against the inner surface portion of theelectrode 28 and on the other hand against the surface of the crystalplate 7.

I claim:

1. A transmitter comprising an electronic valve, a heatin batteryconnected to the heating filament of said valve, a control-quartzconnected on the one hand to the grid of said valve, and on the otherhand to said battery, a choke wound about said valve and connected inparallel to said control-quartz, and an anode battery connected on theone hand to the filament and on the other hand to the anode of saidvalve, a morse key interconnected between said anode battery and saidanode, a rotary plate condenser interconnected between said morse keyand said anode, and a condenser bridging said anode battery, all saidparts being arranged in a casing of pocket size.

2. A transmitter comprising an electronic valve, a heating batteryconnected to the heating filament of said valve, a control-quartzconnected on the one hand to the grid of said valve, and on the otherhand to said battery, a choke wound about said valve and connected inparallel to said control-quartz, and an anode battery comprising acasing, a great number of single elements set together, and adry-element filling arranged in said casing, said anode batteryconnected on the one hand to the filament and on the other hand to theanode of said valve a morse key interconnected between said anodebattery and said anode, a rotary plate condenser interconnected betweensaid morse key and said anode, and a condenser bridging said anodebattery, all said parts being arranged in a casing of pocket size.

3. A transmitter comprising an electronic valve, a heating batteryconnected to the heating filament of said valve, a control quartzconnected on the one hand to the grid of said valve, and on the otherhand to said battery, a choke wound about said vaive and connected inparallel to said control-quartz, and an anode battery comprising acasing, a great number of circular or rectangular zinc and carbon discsset together and a dry-element filling arranged in said casing, saidanode battery connected on the one hand to the filament and on the otherhand to the anode of said valve a morse key interconnected between saidanode battery and said anode, a rotary plate condenser interconnectedbetween said morse key and said anode, and a condenser bridging saidanode battery, all said parts being arranged in a casing of pocket size.

4. A transmitter comprising an electronic valve, a heating batteryconnected to the heating filament of said valve, a control-quartzconnected on the one hand to the grid of said valve, and on the otherhand to said battery, a choke wound about said valve and connected inparallel to said control-quartz, and an anode battery connected on theone hand to the filament and on the other hand to the anode of saidvalve a morse key interconnected between said anode battery and saidanode, a rotary plate condenser interconnected between said morse keyand said anode, and a condenser bridging said anode battery, all saidparts being arranged in a casing of pocket size, said morse key arrangedon a wall of said casing.

5. A transmitter comprising an electronic valve, a heating batteryconnected to the heating filament of said valve, a control-quartzconnectrotary plate condenser interconnected between,

said morse key and said anode, and a condenser bridging said anodebattery, all said parts being arranged in a casing of pocket size, saidmorse key arranged at a lid of said casing.

6. A transmitter comprising an electronic valve, a heating batteryconnected to the heating filament of said Valve, a control quartzarrangement comprising two thin metal discs, one insulating ringmaintaining said metal discs in a certain distance of one another, aquartz disc arranged between the said metal discs, a thin spring discarranged between said quartz disc and one of said metal discs to pressthe quartz disc against the other of the said metal discs, said metaldiscs connected with the grid of said electronic valve on the one handand with said heating battery on the other hand, a choke wound aboutsaid valve and connected in parallel to said control-quartz, and ananode battery comprising a casing, a great number of circular orrectangular zinc and carbon discs set together and a dry-element fillingarranged in said casing, said anode battery connected on the one hand tothe filament and on the other hand to the anode of said valve a morsekey interconnected between said anode battery and said anode, a rotaryplate condenser interconnected between said morse key and said anode,and a condenser bridging said anode battery, all said parts beingarranged in a casing of pocket size, said morse key arranged at a lid ofsaid casing.

'7. A transmitter comprising an electronic valve, containing twoentirely separate systems, each of said systems comprising a grid, plateand filament, each two of the said corresponding electrodes beingconnected in parallel within the valve, a heating battery connected tothe heating filament of said valve, a control-quartz connected on theone hand to the grid of said valve, and on the other hand to saidbattery, a choke wound about said valve and connected in parallel tosaid control-quartz, and an anode battery connected on the one hand tothe filament and on the other hand to the anode of said valve a morsekey interconnected between said anode battery and said anode, a rotaryplate condenser interconnected between said morse key and said anode,and a condenser bridging said anode battery, all said parts beingarranged in a casing of pocket size, said morse key arranged at a lid ofsaid casing.

HEINRICH EBERHARD.

